The present invention relates generally to an induction foil cap sealer, and specifically to a modular induction foil cap sealer that is efficiently cooled without the use of either cooling water or forced air cooling.
It is known in the art to secure metal foil seals to the cap of a container by passing the cap with the metal foil seal seated on it through a magnetic field generated by applying a high frequency current to an inductor coil. The magnetic field inductively heats the metal foil, which in turn heats and cures a sealing material adhering to the foil. The sealing material, typically a thermoplastic resin, sets and seals to the lip of the container""s opening. Known foil cap sealers have components that require water cooling and/or forced air cooling. For example, the inductor could be a hollow copper tubing or bus bar that is cooled by running water through the hollow passage of the tubing or bus bar. The use of Litz wire, which is known in the art, reduced heat losses to the extent that forced conduction air cooling of the foil cap sealer became feasible. Forced conduction air cooling, with the requirement for one or more typically electrically driven fans, requires additional energy consumption and increases the volume and weight of the foil cap sealing equipment.
Additionally, foil cap sealers known in the art consist of a unitary enclosure that includes the sealing head and a high frequency power supply. The unitary enclosure must be supported and suspended over a processing line that transports the caps of the containers under the sealing head to heat the foil seals. This arrangement substantially increases the weight that must be supported over the processing line. Additionally, failure in the power supply or failure in the sealing head will necessitate the replacement of the entire foil cap sealer""s unitary enclosure.
Therefore, there exists the need for a modular air-cooled, energy efficient induction cap sealer that will not require forced air or water cooling.
In one aspect, the present invention is an induction foil cap sealer that is used to secure a foil cap to the cap of a container. The foil sealer includes a sealing head module and a power supply module. A coil assembly is provided in the sealing head module. The coil assembly includes a magnetic flux concentrator, such as a ferrite core, and an air-cooled inductor disposed adjacent to the magnetic flux concentrator. In one embodiment of the invention, a frame surrounds the sides of the core and a cover plate is attached to the top of the ferrite coil and inductor. At least one evaporator element of one or more heat pipes is in contact with the magnetic flux concentrator. A thermally conductive material, such as a coil plate, may be inserted between the magnetic flux concentrator and the at least one evaporator element. Means are provided for connecting the evaporator elements to at least one condenser element of the one or more heat pipes so that the heat pipe""s heat media can transfer heat from the evaporator to the condenser elements. In one embodiment of the invention, the inductor is a Litz wire that is seated in a ferrite core. The ferrite core is formed from U-shaped ferrite segments. A control panel may be included with the sealing heading module or may be remotely located.
In another aspect the present invention is a method of sealing a foil cap seated on the cap of a container to the cap. A sealing head assembly is provided with an air-cooled inductor disposed adjacent to a magnetic flux concentrator, such as a ferrite core. An ac current is provided to the inductor from a power supply that is located remotely from the sealing head assembly. Current flow through the inductor creates a magnetic field that generates heat in the ferrite core. Generated heat is transferred to ambient air without the requirement for water cooling or forced air cooling. These and other aspects of the invention are set forth in the specification and appended claims.